The present invention relates to a device for sampling blood and measuring erythrocyte sedimentation rate. More particularly, it relates to a device which functions as a tube for measuring erythrocyte sedimentation rate as well as functioning as an evacuated tube for sampling blood. That is, the device is designed so that blood can be directly placed into the device from a vein and an erythrocyte sedimentation rate of the sampled blood can be measured in the device without pouring the blood into another measuring tube.
Heretofore, the measurement of erythrocyte sedimentation rate of blood was carried out by sampling blood of the human body by means of a blood sampling device such as an injector, pouring the sampled blood from the blood sampling device into an erythrocyte sedimentation rate measuring device and measuring the erythrocyte sedimentation rate in the measuring device.
However, the conventional method has a drawback that since a measuring device is separate from a blood sampling device, the sampled blood must be poured from the sampling device into the measuring device, which is a troublesome operation.
In order to overcome this drawback, the present applicants disclosed a device serving as a blood sampling tube and as an erythrocyte sedimentation rate measuring tube in Japanese Utility Model Application No. 158997/1984 (filed on Oct. 20, 1984) which was published on May 19, 1986 under Japanese Unexamined Utility Model Publication No. 73303/1986.
The device disclosed in the earlier application is a tube with one end closed; a blood sampling portion on the open end of the tube; an erythrocyte sedimentation rate measuring portion extending from the blood sampling portion. The open end of the tube is stoppered with a stoppering means such as a rubber plug to keep the inside of the tube at a vacuum. The stoppering means can be pierced with a blood drawing needle. A scale for measuring erythrocyte sedimentation rate is provided on the surface of the measuring portion of the tube which is transparent or translucent, or on the surface of a transparent or translucent outer tube in which the measuring tube is inserted. The measurement of an erythrocyte sedimentation rate using the above-mentioned device is carried out as follows: one end of a blood drawing needle is inserted into a vein and other end of the blood drawing needle is inserted into the blood sampling portion of the evacuated tube through the rubber plug. Blood is drawn into the tube through the blood draing needle due to the vacuum in the tube. The blood introduced in the tube is mixed thoroughly with an aqueous solution of an anticoagulant, such as an aqueous solution of sodium citrate, which has been previously placed in the tube. The mixing is effected by turning the tube upside down to allow the blood to flow down to the top of the be in the normal position, followed by repetition of such procedure. After the mixing is completed, the tube is stood vertically on a stand and the measurement is carried out.
With respect to a tube for measuring erythrocyte sedimentation rate, the International Standard relating to the Westergren method provides that the length of a scale portion of the tube be 200 mm.
Accordingly, the measuring portion of the above-mentioned device also must have a length of 200 mm in order to adapt the device for the Westergren method.
On the other hand, it is desirable that the amount of blood used to measure erythrocyte sedimentation rate is as small as possible. In order to reduce the amount of blood used, the inner diameter of the measuring portion of the tube is reduced so long as the length of the measuring portion is 200 mm. For example, when the amount of blood used is less than 3 m, an inner diameter of less than 4.4 mm is required.
However, such smaller diameter of the measuring portion causes an adverse effect on flowing of blood in the abovementioned mixing operation, which requires a long period of time mixing blood with an anticoagulant solution.
It is an object of the present invention to provide a device for sampling blood and measuring erythrocyte sedimentation rate which is capable of sampling blood directly thereinto and mixing the sampled blood with a solution of an anticoagulant quickly and easily.
This and other objects will become apparent from the description hereinafter.